1. Field of the Invention
This invention relates in general to a system for providing electrical continuity between a plurality of circuit boards, and in particular to a method and apparatus for improving the packaging and distribution of power to high performance electronic circuit assemblies.
2. Description of the Related Art
As electronic circuitry becomes more complex, packaging of the circuitry has become more difficult. The common method for packaging integrated circuits (ICs) and other electronic components is to mount them on printed circuit boards (PCBs) or other substrates such as ceramics having alternating conductive and non-conductive layers or planes sandwiched or bonded together to form a dense X-Y signal interconnect. For a number of years, the operating voltage of ICs was approximately 5 volts and the power consumption was generally less than 1 watt. This relatively high supply voltage and low power level allowed the packaging of a large number of ICs on a single PCB with power distribution incorporated into one or more of the PCB planes.
More recently advances in silicon fabrication techniques have permitted the manufacture of high performance IC packages with operating voltages at or below 1 volt and power levels in excess of 100 watts. As described in co-pending and commonly assigned patent application Ser. No. 09/785,892, METHOD AND APPARATUS FOR PROVIDING POWER TO A MICROPROCESSOR WITH INTEGRATED THERMAL AND EMI MANAGEMENT, by Joseph T. DiBene II, David H. Hartke, James J. Hjerpe Kaskade, and Carl E. Hoge, filed Feb. 16, 2001, which application is hereby incorporated by reference, the transient current to some of these packages can exceed hundreds of amps per microsecond. To assure optimum performance under these conditions, it is important that the electrical path from the power supply to the IC be designed to accommodate high current flow and low series inductance, two goals which are difficult to achieve at the same time. The present invention achieves both of these goals, while also allowing for a compact, integrated stack-up system design that permits thermal dissipation and control of electromagnetic interference (EMI).
To address the requirements described above, the present invention discloses a method, apparatus, article of manufacture, for providing power from a first circuit board having a first circuit board first conductive surface and a first circuit board second conductive surface to a second circuit board having a second circuit board first conductive surface and a second circuit board second conductive surface. The apparatus comprises a first conductive member, including a first end having a first conductive member surface electrically coupleable to the first circuit board first conductive surface and a second end distal from the first end having a first conductive member second surface electrically coupleable to the second circuit board first surface. The apparatus also comprises a second conductive member, having a second conductive member first surface electrically coupleable to the first circuit board second surface and a second conductive member second surface distal from the second conductive member first surface electrically coupleable to the second circuit board second conductive surface. In one embodiment of the invention, the second conductive member is hollow, and is disposed within the second conductive member in a coaxial arrangement. If desired, a dielectric can be placed between the first conductive member and the second conductive member. The dielectric, or the dimensions of the first conductive member and the second conductive member can be defined so that the apparatus exhibits an impedance that can be used cooperatively with circuit elements on either the first circuit board or the second circuit board. One of the advantages of the present invention is the integration of function in which the apparatus operates both as a rigid standoff to separate the first circuit board from the second circuit board, and a conduit for delivering power and a ground return (or other signals) between the circuit boards as well. While the apparatus will be discussed in terms of providing a power signal from a first circuit board to a second circuit board, it can also be used to provide power to a plurality of circuit boards in a stacked up configuration, all with minimal impedance.